Researchers at a major Texas health science institution have traced a remarkable moment in human history to roughly a million years ago, when the global population is estimated to have been as low as about 1,300 individuals. This finding, derived from a careful study of ancient genetic footprints, has been reported in a prominent science publication. The event is described as a bottleneck, a sharp drop in the gene pool that occurs when a population undergoes a dramatic, temporary decline in numbers for a variety of possible reasons.
To reconstruct this episode, scientists introduced a cutting-edge method called FitCoal, designed to model how population size changed over time by analyzing modern genetic data. By studying the genomes of 3,154 people, researchers were able to chart broad patterns of demographic shifts across vast stretches of prehistory, gaining a clearer view of how ancestral populations evolved and moved over millennia.
The analysis indicates that our distant ancestors endured a bottleneck in which the effective breeding population hovered around 1,280 individuals roughly 930,000 to 813,000 years ago. The bottleneck persisted for an estimated 117,000 years, a long period during which the human lineage stood on the brink of extinction. These results shed light on a critical chapter in human evolution, illustrating how vulnerable early populations could be to environmental stressors and other upheavals.
Researchers note that a period of intense cooling coincides with this era, a climate shift that would have drastically altered habitats and food resources. Some scientists also propose that meteor impacts could have contributed to the rapid reductions in population size, compounding the challenges faced by early humans as they struggled to survive in changing landscapes.
Beyond mere numbers, the study suggests that coming out of this bottleneck helped shape the course of the Homo genus. As populations recovered and expanded, genetic diversity increased again, laying groundwork for the later diversity observed in human groups around the world. These insights help explain why modern humans, despite their relatively small ancestral populations, achieved a wide geographic distribution and complex cultural development over time.
In broader historical terms, researchers highlight how the interplay between climate shifts, astronomical events, and human resilience contributed to the enduring narrative of human evolution. The findings illustrate that even small, tightly knit groups could contribute to the genetic tapestry that defines humanity today, underscoring the remarkable adaptability of our species and the enduring influence of ancient population dynamics.